I am looking a bit around on the new MemoExecDQL function, so I downloaded the MemoAndExecDQLSample, but for the life of me I cannot find out what credentials to use to have full access and see the source code.

Have you tried 

http://www.dataease.com/DG3_BlogList/?ParentID=000...

also

How to get it to work.

Download and install the latest DataEase 8. Open the Zip and copy the entire catalogue to My DataEase under My Documents. Open DataEase and Open Application MemoAndExecDQLSample

Usermode:
Username: User
Password: User

Developer Mode:
Username: High
Password: High

Searching the Forum and blog for the words "Sample"  and the word MemoExecDQL return results that might help.

You might want to check the version of your DataEase.

In DE8.2 you should always be able to switch to Design Mode if you are logged in with a High user. 

The developer is for developing/testing so logging in with a startup-document now is just for testing in Developer, it will not lock the application to RT.

That's it, High - High, you should put them in a README.TXT file inside the zip package.